This is a 14mm ceramic nail without a dome. This nail will fit on any water pipe that has a 14mm joint. Most of our nail has the dual fitting so it also can work with 10mm joint size. It's female nail.
This ceramic piece has a 14mm male fitting on one end, and a female 18mm fitting on the other end. Good build quality, sure to last you a while. Total length of the adapter is roughly 1 and a half inches.